The U.S. Supreme Court is expected to hear arguments Wednesday on the Voting Rights Act and a requirement that keeps some states under federal oversight.
The Voting Rights Act requires places with a history of voting discrimination to get approval from Washington before making any election-related changes. That includes even changing the location of a voting precinct.
The appeal was filed by Shelby County, Ala. Mississippi is also under federal oversight.
Opponents say they no longer should be forced to live under the thumb of Washington because the country has made enormous racial progress.
The Obama administration and civil rights groups are defending the provision.
But the law allows governments that have changed their ways to get out from under this provision.
Nearly 250 counties and local jurisdictions have done so, and thousands more could be eligible.